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Washington (CNN)Hillary Clinton and Bernie Sanders are set to meet Tuesday night in Washington -- a step that could help Democrats avoid a contested convention.

Sanders revealed plans for the meeting Sunday on CBS' "Face the Nation," and a Clinton aide confirmed to CNN that it is planned for Tuesday night. The aide didn't offer details on where or when it would take place.

Sanders emphasized the importance of the Democratic platform in his interview with CBS' John Dickerson, signaling that he's looking for concessions there in order to avoid a contested convention.

"I will be meeting, as I understand it on Tuesday night with Secretary Clinton, and I will get a sense from her about the nature of the Democratic platform," Sanders said.

Pointing to issues like income inequality and health care, Sanders said: "I look forward to sitting down with Sec. Clinton to see what kind of platform she is going to support and in fact how aggressive she is going to be in addressing the major crises that we face."

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The meeting comes the day the District of Columbia will hold the final primary contest of the 2016 election season. Already, Clinton has locked in advantages in overall delegates, pledged delegates and the popular vote ahead of the Democratic convention in Philadelphia in July, and she has been declared the party's presumptive nominee.

But Sanders has remained in the race and is campaigning in Washington. Clinton already planned to be in town Tuesday night for a fundraiser after campaigning in Pittsburgh earlier in the day.

Democratic officials quickly consolidated behind Clinton last week after she won enough delegates to become the presumptive nominee. President Barack Obama and Massachusetts Sen. Elizabeth Warren -- a progressive icon -- both endorsed Clinton, and even some of Sanders' strongest backers conceded the nominating contest is over.

Sanders had previously insisted he would continue his campaign through the convention, but he and his aides have been more muted about his plans in recent days.